The objective of this Phase I:II study is 1) to evaluate and compare the safety and dose tolerance of intermittent daily dosing regimens of oral tucaresol in patients with metastatic melanoma; 2) to explore the dose vs. immune stimulatory effect relationship of tucaresol; 3) to perform a limited investigation of the pharmacokinetics of tucaresol when administered orally in daily dosing regimens; 4) to obtain a preliminarily assessment of the anti-tumor activity of tucaresol in patients with metastatic melanoma.